Recovery apparatus



Aug. 3, 1943.

M. S. ROBERTSON REQOVERY APPARATUS Filed July 29, 1940 Hi5 ATTORNEY INVENTOR MIL Patented Aug. 3, 1943 I i 232x8 Y VMy invention relates to apparatus ing particles of material; andmore for separatdensity. a 1

It isamong the objects ofmy invention to proa video improved apparatus for separating small par ticles of finely divided material; i

I i Another objectis to provide'apparatus for recovering fine gold from sand. l 1 A further object is to provide a fluid counterfiow apparatus embodying means for eliminating eddy currents so as to effectively separate finely divided material, I

r The invention possesses other objects and features of advantage, some of which, withthe foregoing, will be set forth in the following descrip tion of my invention; It is to bei understood particularly to a devicefor separatingparticles of difierent In'greater detaiLand referring to Figures 1 and 2t of the drawing, my apparat'us'as' adapted for recovering fine goldfrom sand comprise a that I do not. limit myself to lthis'disclosure or species of my invention, as I may adopt variant embodiments thereof within" the scope of the claims; 7 1 a e Referring to the drawing:

Figurel is aside View; partly in elevation, embodying and l partly in section and the improvements of my invention;

Figure 2 is a transverse verticalsectional view 7 of the same, taken in a plane indicated byline 2-2 of Figure 1. 7

Figure 3 isa fragmentary plan view showing a modified construction.

showing a recovery apparatus" of'troughz is preferably corrugated to Many black-sands, such as found on ocean beaches, contain fine gold in quantitie justify ing its recovery if suitable equipment is available for effecting its separation. most unlimited opportunityfor 'livelihood to per; sons not otherwise employed, providing an efficient recovery unit may be had which is portable and easily operated. While the apparatus of my invention'is particularly well adapted for use-in small units into which the sand is-shoveled" by an individual operating his own equipment, it may also be operated with auxiliary power equipment and used in banks of units for-larger seale operations. i i

In terms of broadginclusion, my recovery 'apparatus comprises a separating station including a counterflow of fiuid for separating dense from lighter particles of material,- and means for pre-' venting eddy currents in the cou'nterflow to effect eflicient separation between' parti'cles of finely divided material; A plurality -of-.these separating stations are preferably provided; and meansare provided for controlling the counterflow at the I stations This offers an ale from li'ghter particles.

trough. 2 havingv az'hopper 3 formed atone end for receiving sand 4 containingthe gold. The apparatuslillustrated is a small capacity unit have all lengtheof the trough and hopper being about may-be used in banks*in --larger'scale -opera= tions. WhileI have 'shown an' open-top, trough, a closed trough or pipe could; be used "through which the sand or material passes. i

Aslidable' gate Bis preferably arrangedat the head of the troug'h for controlling fiow'o-f sand from hopper3; the position of-this gate determin ing the slope of sand bar 'l-extendirig into the;

troughs Hopper-'3has a slopin'g bottom"8fand'a duct 9 is preferably provided for feeding a small stream of water into the hopper tokeep the sand moving uniformly into the trough. a The .bottom v de a series of longitudinally extending V'-'shapejd channels ll'to facilitate'cleaning up after a daysflr un If desired however, aflat bottomed trough may beused. a v w 'A-separ'ating stationisarranged in the trough ahead of sandbar 1, and counterfiow means are provided at the station for separating the dense For thispurpose a group of up'right ducts ortubes 12, preferably disposed in. a' transverse' row,-"are ported into the; bottom of the trough in registration with channels I l at;

the foot of sand'bar 7. While I have shown four I tubes in a row, it is-understood that a different number may be employed." Thus in a trough twelve inches wide," a-group oftwelvetubes is y preferably used, the tubes being-approximately one inch in diameter; Water is introduced into the tubes from a supply manifold l3 through aheader' having branch'ducts l 6 opening into't'he sides of the tubes. The flow of water is regulated by 'a suitable valve [1 in header l4, anda' uniform ilow of fluid into' the severaltubes is insured by orificed inserts I 8in branch ducts V v 16. A tank It! is provided atthe lower-ends of the tubes for receiving the denseparticles of material" and to providers, losure so thatthe Water isdirected upwardly through the tubes. "Ifhe reduced ends of the tubes seat in necks-Zion the tank to provide a tightv joint, yet permit removal of the tank for 7 taking out the collected values. In order to precess waterfrom pool 23 discharges'over rifiie plate 24 and the lighter particles carried over the plate build up a second sand bar 26. Asa matter of fact, this second sand bar will form by reason of sand deposited on the bottom of the trough without the presence of plate 24, and in such case Venturi passage is preferably such as to prevent gold particles from collecting on the rim.

A series of say three separating stations are preferably arranged along the trough, each having a group of counterflow tubes l2 similar to those described for the first station. Riffie plates 28 and 29 for the second and third stations are preferably shorter than rifile plate 24; the latter having the greatest height to dissipate surges in the water originating at the intake: end. The sand carried with the discharging water over the first riflle plate '24 and moving down along bar 26 intercepts the counterfiow at the second stathe sand bar itself forms a rifile. The presence of a rigid riiiie plate 24 however prevents surges of water from washing out the Sandbar. By the term riiile as used throughout the specification and claims I mean any suitable barrier such as V plate-24 orsand bar26'without the plate.

As the incoming sand flows into thertrough along'bar -I it falls into tubes :12 and is met Joy the counterflow of'fiuid.-- Thedensen goldpartie cles iall against thecounterflow and are deposited intank lflywhile. the lighter sandparticles are 1 carried off with the fluid discharging; over riiiie plate 24. The turbulence of the water in pool 23 keepsthe particlesv moving while the separation takes place; the lighterparticles being urged upwardly over; the riffie andthe heavier. particles gradually: settling down alongthe tubes underthe influence otgravity. This turbulence in pool .23

the counterflow being such that some of the .finer gold iscarried over the riiile;,with= the sandv for recovery atother stations.

, An -important;feature-of my invention is the provision of the groupof relativelysmall counterfiow tubes atthe separating station; It asingle 3 largecounteriiow tube were employed, through relatively largecolumn of water flowed, therewould beeddycurrents set up in the tube that would destroytheuniformity or the counter:

flow and allow other materialto fallthrough with which a the gold. This eddy; current problem is one of the principal reasons why counterfiow systems have not been successfulffor recovering'fine gold. Inmy improvedapparatus this lis overcome-by dividing the counterfiow intorai-group ofvrelatively small Water colurnns, thus maintaining the o capacity of the unit problem. -While I ;ha ve shown separate-tube l2,

it is understood that they maybe integrally con-' without, the; eddy current nected in the group, Thus an elongated box-like structure could be employed,- divided by partitions into a plurality of tubes or ducts; Sucha cellular: structure would serve equally well to" die vide the fiow into a" plurality of columns :to re- Al ou h:

tard the formation of eddy currents.- I showa single row oftubes or ducts at each station it is understood, that. additionalrows may be addedin the groups 1 H 1 In order to further improve the separating actionfa Venturi passage isperferably: provided in each tube by a suitably shaped insert TL-The throat of this Yenturipassage is preferably quite long, as shown in Figurev 1, todissipatesurges in the water and insure a uniformcounterfiow against which the I fine gold particles may settle Q d Ti ed??? si -the u pe fl r n d-:9 the tion and is subjected again to the separating action. Counterfiow atthe second station is regugold particles to settle out.

also aids inkeeping the incomingsand moving a down along bar] "until -it is'. entrained by-the counterflow. -Valve ll .isi preferably adjusted so that only; the larger gold particles' are allowed to settle out at ;th'lS'fiISI/ statior'i-ythegforcefof The still finer gold particles are again discharged with the sand over riflie plate 28 and movealong bar33 -torthe laststation. Here the force'of the counterflowfisstillless and thevery fine values are recovered; Another important feature of my invention therefore is the passage of the material through a series of separating stations,,and regulating the. counterfiow to progressively decreasentheforce 'oi the now at: successive stations to control the separation. Such procedure gives good recovery andfaster'action'. It is understood or course that additional stations, maybe employed; although with a, threestation unit I have recovered as-high'as ninety eight percent of the free goldinib-la'ck sand.

From riiile 29 of the last station thesand forms another bar 34 and the fluid-and sand are finally discharged fromthe trough over an end rifile 36. Somejvalues collect aheadsof this end riiile end to control the water level 38 behindxriflie plate 26. 7.; a

Instead of flat; riflie plates a modifiedfform shown in Figure B may be used; This type comprises semi-circular sections 39 and is convene iently formedby cutting away the forward half 7 of projecting ends of tubes l 2,- ;The c'oncavities inthis riiile'plate lead to asomewhat-different fluid motion and the separating action isigocdv If. desired, the apparatus may be used to recover the lighter particles, in which case the ma-1 terial discharging from the tail endfof the trough Wouldbe collected. 7 i Iclaim:

r l. Becoveryapparatus"comprising atrough for receiving material to b separated and having a.

bottom with a plural tyof-longitudinally extending V-shapedchannels, and;a groupvoi' upright tubes extending from thejbottonr of -,th'e-trough in. registrationf witlr said channels and through which the denseparticles may'fall, and means-for.v establishing a counterfiow o2 fluid upwardly through said tubes.

2. Recovery apparatus comprising a trough, a

group of counterfiow tubes arranged in a: row

disposed transversely eithetrough and opening intothe bottom portions thereof, saidtubes be-; ing sealed againstpomrnunication at the lower ends to prevent recirculation through the tubes, a header ior supplying fluid; ducts connected with the header"andopenihginto;the sides of said WW 0W s lii ti e means interpos d in ea h of said ducts,- and means in said'header ior"controlling t e uis I j MILTON S. ROBERTSONe 

